In order to successfully exploit subterranean hydrocarbon reserves, information about the subsurface formations and formation fluids intercepted by a wellbore is generally required. This information may be obtained via sampling formation fluids during various drilling and completion operations. The fluid may be collected and analyzed, for example, to ascertain the composition and producibility of hydrocarbon fluid reservoirs.
In order to obtain a reliable characterization of the reservoir fluid, it is desirable to minimized drilling fluid contamination, for example, via pumping sampled fluid overboard until contamination levels reach an acceptably low level. Such a process can be time consuming as it sometimes requires pumping hundreds of liters of fluid overboard. Increasing the flow rate can be problematic as pumping too rapidly may reduce the flowline pressure below the saturation pressure of the fluid and thereby result in the formation of a second phase in the fluid (e.g., formation of gas bubbles or liquid condensate). Such bubble or dew formation can in turn decrease pumping efficiency and may further degrade optical spectroscopy measurements used to determine fluid contamination.
There is a need in the art for a method and apparatus for pumping formation fluid as rapidly as possible without drawing the flowline pressure below the saturation pressure of the fluid.